Described herein are methods for extending the life of a fuser member, and materials for use in such methods. More in particular, described are methods and materials for removing potentially damaging materials from a fuser member surface.
Fuser members may be utilized in many different applications for fusing and/or fixing a toner image to an image receiving medium. For example, a fuser member may be used in electrophotographic and/or xerographic devices (e.g., copying machines), facsimile devices, printers, and the like.
In a typical electrophotographic or xerographic process, a photoconductive member is charged to a substantially uniform potential so as to sensitize the surface thereof. The charged portion of the photoconductive member is exposed to a light image of an original document being reproduced. Exposure of the charged photoconductive member selectively dissipates the charges thereon in the irradiated areas. This records an electrostatic latent image on the photoconductive member corresponding to the informational areas contained within the original document. After the electrostatic latent image is recorded on the photoconductive member, the latent image is developed by bringing a developer material into proximity therewith. Generally, the developer material comprises toner particles adhering triboelectrically to carrier granules. The toner particles are attracted from the carrier granules to the latent image forming a toner powder image on the photoconductive member. The toner powder image is then transferred from the photoconductive member to an image receiving substrate such as copy paper. The toner particles are heated at a fusing station to permanently affix the image to the copy sheet.
In order to fuse the image formed by the toner onto the paper, electrophotographic devices include a fuser. While the fuser may take many forms, heat or combination heat-pressure fusers are currently most common. One combination heat-pressure fuser includes a heat fusing roll in physical contact with a hard pressure roll. These rolls cooperate to form a fusing nip through which the copy sheet (the sheet on which the document is finally formed) passes.
Fuser rolls are typically in the form of a rotating cylinder, with an outer surface comprising a thin elastomeric layer that contacts the copy material. The outer surface may include a release agent, such as silicone oil, to prevent toner from adhering to the surface of the fuser roll itself. Fuser rolls commonly used have outer layers of a thickness on the order of 0.002–0.07 inches (2 to 70 mils), while typical pressures exerted on the outer layer of a fuser roll are on the order of 50 to 150 psi.
The life of a fuser member is limited by several failure mechanisms. The surface or bulk properties of the elastic material used for coating of the roll can, for instance, become degraded by prolonged exposure to high temperature. Another mechanism is the wear of the roll caused by paper abrasion. Still other mechanisms include the attachment of high molecular weight materials such as oligomers or other decomposition products of the silicone oil release agent commonly employed in fuser systems. The formation rate of these products may be increased by the presence of impurities (for example, toner components, paper components or environmental contaminants). Additionally, some of these contaminants may react in the fuser nip, forming a polar salt layer that covers the surface of the roll. When this occurs, toner from the image is more prone to offset to the fuser member surface and be re-deposited at another part of the print or copy. Such toner offset to the fuser member surface is undesirable and results in degraded image quality. This adhesion of toner to the roll is also believed to be a first step in the cascade leading to stripping failure, wherein the image receiving substrate adheres to the fuser member surface rather than being easily stripped therefrom, and ultimately to fuser member failure.